Circuit breaker



Dec. 16, 1952 J. B. cATALDo ErAL 2,622,159

CIRCUIT BREAKER Filed May 17, 195o 2 SHEETS- SHEET 1 /fa f5 /9 HJ f2@ /2 ff@ j J. B. cATALDo ErAL 2,522,169

CIRCUIT BREAKER lDec. 16, 1952 Filed May 17, 1950 2 SHEETS-SHEET 2 Patented Dec. 16, 1952 UNITED STATES PATENT QFFICE CIRCUIT Baastian J ohnB. Cataldo, Bernardsviile, Elbert `De F. Tidei, Clinton', and Albert N. Cock, Millington, N. J.. assignorsv toJohn B. Pierce Foundation, New York, N. Y., a corporation of New York Application May 17, 1950', Seria-l No. 162,49i2

'7' Claims.

This invention relates to thermbresponsive snap switch devicesl and more particularly to circuitl breakers using thermoresponsive snap springs as the sensing and actuating components therein.

In the design of circuit breakers it is' often diicult to achieve specific current rating and electrical Contact pressure characteristics without exceeding reasonable manufacturing costs. Particularly is this true in circuitbreakers of the auxiliary type suchl asmight be' used in the individual feeder lines to each piecel ofl electrical equipment among a group, these' auxiliaryV breakers being useful in preventing a s'hutdownf of an entire plant when a single piece of equipment is at fault.

It is, therefore, an object of thisn invention to provide a circuit breaker which'may be manufactured economically notwithstanding` precise standards in the operating characteristics.

A further object of this inventionis to provide a circuit breaker comprisinga' novel assembly of components which afford trip-#free operation in which reclosing ofthe electrical circuit is effected subsequent to and not during resetting action.

To achieve the'above and otherfobjects'according to the invention, a bimetallic snap spring disc adapted to snap between two congurations and carrying electrical contacts is fitted' loosely on a movable carrier, and a second' spring'ele'- ment such as a monometallic spring disc for example, is reacted between a stationary abutment and the snap disc tourge"r thelatter against theVV carrier, thereby to` provide aloose; coupling assembly which is highly-v effective as well'as economical. In order to preventthe snap, disc from rotating on thecarrier, the'electrica'ljcon'- tacts or other suitable radial extensions areprovided which protrude beyond the-rmjof the disc to be received in suitable elongated guide channels formed in the housing.` Resetting-is accomplished by displacing'th'esnap discfirr translational movement in order that the snapt disc may be forced onto its iriitial4 configurationwithout concurrently closing!V the?- electrical- V lcircuit through the circuit breaker,- the-`latter stepbeing performed in a separate and'subseduent operation. y a y For abetter understanding of thefab'ove' andV other features and advantages referencemay be had tothe following specificationofV representa--A (Cl. 20G-4155) 2 breaker assembly embodying the present invention taken on the line I"-Ilv of Fig. 2 looking in the vdirection of thev arrows;

Fig. 2 is a view in horizontalcross section taken on the line 2.-2 of Fig. l' looking in the direction of the arrows;

Fig. 3 is a side view in' cross section similar to Fig. lshowing the circuit breaker mechanism in tripped position; f

Liris a side view in cross section slfi'owin'gI the circuit breakerl mechanism subsequent to the rststep in the resetting operation;

Fig. 5 is a bottom view in an electrical plug' or cord cap havingthe novel circuit breaker mechanisrn incorporated therein; l

Fig', 6 is' a View in longitudinal' cross; section takenl onV the line? o o of Fig. 5 looking in the directionof the arrows; i

Fig. 7 is a view in longitudinalvcross section of a modied'form of the circuit breaker adaptable for installation on a panel4 board takenon the line T-'I ofrFig. 8 looking in the direction of the arrows, and Y Fig'. 8 is aside View in` cross section of the unit shown inv Fig. '7 taken on the line 8 8 looking in the direction of the arrows.

Referring to Figs. 1' and' 2 of the drawing, the invention will be seen asv embodied in a circuit breaker unit comprising an insulating lower housing portion It having a cylindrical recess I formed therein and an upper annular cap portion' I I also formed of insulating materialand affixed to the lower portion by suitable means suc'h'asI screws Si.

The cap portion I i defines a cylindrical open-` ing I Ia of substantially the same diameter as the cylindrical recess IIl and is internally formed with an annular shoulder I2 definingan'opening |221; ofl srnaller diameter than the recess Illa. The lower housing portion Iii is formed with a central bore I3 into which is threaded a bushing I4 which in turn slidably receives a. push-shaft or carrierv I5.' The push-shaft I5. is formed adja cent its inner end with a shoulder stop Iiin which y engages the inner end ofthe bushing Iflto determine the outermost position of` the push-shaft.

A dished` birnetallic snap spring disc Il of slightly smaller diameter than the recess Ilia is mounted within the housing tov partakeof peripheralsnap movement, the mounting being ef-` feuc'ted by means of acentral aperture formed in thedisc which loosely receives the inner end of the push-shaft I5. The snap spring disc' I1 is urged a-gainst'jthev stop shoulderV IS by a' dished sp'ringdisc I3 which is also *centrallyY ap'ertured to receive the inner end of the push-shaft I5, the spring disc being reacted between the center portion of the snap spring disc I'I and the annular shoulder I2 formed on the housing. Normally part of the spring force of the spring disc I8 is carried by the snap spring disc II through peripheral contact pressure as described later, and the remainder is carried directly by the housing through the engagement of the shoulder IE with the stationary bushing i4. Preferably an insulating spacer washer I9 is iitted on the push-shaft I between the discs Il and I8 to reduce heat loss by conduction between the discs. It will be seen, therefore, that spring disc I3 `and bimetallic snap spring disc I'I are loosely received on the push-shaft I5 with the assembly being maintained only by the spring force of the spring disc I8 as described.

The bimetallic snap spring disc I'I is so constructed that it will snap from its first coniiguration of equilibrium as shown in Fig. 1 to a second configuration as shown in Fig. 3 under the influence of heat which, in the illustrated embodiment of the invention, is developed by current flowing directly through the disc. For a more detailed disclosure of the characteristics, structure and methods of manufacture of bimetallic snap spring discs and monometallic spring discs of the types contemplated for use in the illustrated embodiments of the invention, reference may be had to the following U. S. patent applications: Serial No. 628,447 filed November 14, 1945, entitled Toggle Springs; Serial No. 635,956 led December 19, 1945, entitled Snap Disc Springs and Serial No. 139,182 led January 18, 1950, entitled Snap Springs and Methods of Manufacture. In the instant embodiment of the invention the snap spring disc II is preferably so formed that it will snap from its iirst to its second coniiguration at a given temperature as induced by a current flow therethrough, but will not return to the iirst coniiguration within the ambient temperature range in which the device is to be operated, thus necessitating a manual reset operation as described below.

A pair of electrical contact members 2D and 2| are attached to the periphery of the bimetallic snap disc I'I at diametrically opposite points as by welding or soldering to extend radially outw-ardly from the rim of the disc as shown. The overhanging contacts 23 and 2i are received in vertical guide channels 22 and 23 respectively, formed in the inner wall of the housing portion I6, the channels aiording a guideway for movement of the contacts upon snapping of the disc between its respective configurations as shown in Figs. l and 3. The vertical channels 22 and 23 and overhanging contacts 20 and 2I prevent rotation of the snap spring disc I'I about the axis of the push-shaft I5, thus maintaining the proper angular orientation of the disc II within the housing in order that movable contacts 2U and 2I may engage a pair of stationary contacts 24 and 25 respectively, mounted at the lower extremities of the channels 22 and 23, at such times as the snap spring disc II is disposed in the configuration as shown in Fig. 1.

The snap spring disc I1 is formed of metal to afford an electrical path between the stationary contacts 24 and 25 and suitable conductor leads 26 and 21 extend outwardly from the stationary contacts through apertures formed in the housing to receive external wiring connections (not shown). In operation the normally closed circuit through the bimetallic snap spring disc I I CFI enables the latter to become heated by the passage oi current therethrough. Overheating as caused by overload current induces snapping of of the disc I'I to the configuration shown in Fig. 3, thereby opening the circuit and terminating the current iiow in the external circuit in which the unit may be inserted. Alternatively a supplemental resistance heater may be used to afford the necessary heat to buckle the snap disc.

Resetting may be accomplished by manually forcing the push-shaft I5 inwardly aga-inst the spring disc I8, with the snap spring disc I1 being carried in axial translation until the back surf aces of the protruding contacts 25 and 2I engage the uppervtermini of the guide channels 22 and 23, respectively. Further displacement of the pushshaft causes the disc I 'I to buckle into its initial coniiguration of equilibrium. In this fashion the snap disc member is manually urged into its original configuration as shown in Fig. 4 without closing the electrical circuit through the unit, the axial translation of the snap spring disc I'I having carried the movable contacts 23 and 2I for a distance exceeding the displacement afforded by the snap movement of the disc.

Releasing the push-shaft I5 enables the spring disc I8 to urge the push-shaft outwardly to carry the snap spring disc I'I in axial translation to eiect reengagement of the contacts 29-24 and 2I-25. Thus the push-shaft I5 acts as a reset carrier for the snap spring disc I'I, the carrier being movable between first and second positions as described to effect the resetting action. Accordingly it will be seen that there is provided a duty cycle having trip-free operation in which reclosing of the electrical circuit is accomplished after and not during resetting. Thus the circuit breaker cannot be rendered inoperative, i. e. locked in circuit-closed position, by holding or clamping the push-rod l5 in its inner or resetting position.

Adjustment of the contact pressure and rating adjustment of the unit within a preestablished range may be eiected by screwing the bushing I4 inwardly or outwardly as may be required. Inward movement of the bushing I4 for example, increases the current rating or trip point of the breaker and decreases the contact pressure, Whereas movement of the bushing outwardly increases the contact pressure and lowers the current rating.

The invention is also shown as embodied in an electrical plug or cord cap assembly as shown in Figs. 5 and 6. In this embodiment a cup-shaped outer shell 28 receives a pair of insulating housing sections 29 and 30 which cooperate t0 form a cylindrical chamber for receiving the thermoresponsive disc Il, which is loosely centrally mounted on a push-shaft 3I in a manner essentially similar to that described above with reference to Figs. 1 to 4 with like components being assigned like reference numerals.

The housing portion 30 is formed with a central recess 30a into which is threaded a bushing 32 which in turn slidably receives the push-shaft 3 I. Fitted in the shell 28 over the housing sections 29 and 30 is a cylindrical insert member 33 made of insulating material and formed with an inner recess 33a for receiving the outer end of the push-shaft 3I. The outer or exposed surface of the insert member 33 is recessed at 34 and 35 to receive a pair of conventional conductor prongs 36 and 31 which are endwise secured thereto by suitable means such as screws 38 for example.

acca-1 e9 Adjustment of the operating characteristics of the disc assembly is effected by adjusting the axial` position of the bushing 32, This may be accomplished either through the screw assembly as described above or alternatively by inserting shims or spacers between the bushing and the iloor of the recess 39a as may be required to adjust the axial position of the disc assembly.

Stationary contacts t9 and 40 are mounted in the housing at the lower end of,l the channels 22 and 23 respectively, toA be engaged by the movable contacts 2E! and 2l carried by the. rim of the snap disc l1 when thelatter is disposed irl one of its two configurations.

The insert member 33 is formed with a central bore 4I which slidably receives an insulating push-button 42 aixed to a threaded extension 43 formed on the outer end of the push-shaft 3|. A terminal plate 44 (Fig. 5) is formed integrally withy the prong 3E and a terminal screw 44a is threaded into the plate to receive one conductor of a conventional Z-wire electrical cord (not shown). The prong 31, on the other hand, is electrically connected by conductor (not shown) to the stationary contact Ml. The stationary contact` 39 is electrically connected to a terminal plate i5 (Fig. 5) secured to the insert member 33 by a screw dii. A terminal screw 45d is threaded into'the plate 45 to receive the second wire of a 2-wire electrical cord to which the plug is secured. Thus a circuit is provided between the terminal screw Ma and the prong 3lV which includes the snap spring disc member H and the normally closed contacts 20-39 and 24-40.

Operation of the unit is essentially similar to that described above, with overload currents causing the snap spring disc Il to reverse its conguration to open circuit and with resetting being accomplished by pressing inwardly on the push-button 43 to cause the snap spring disc Il to reverse its configuration. Release of the pushbutton enables the spring disc I8 to return the snap spring disc il to circuit-closed position.

Another embodiment of the invention is shown in Figs. 7 and 8 in which the circuit-breaker assembly is incorporated in a panel board unit, the construction and operation of which is essentially similar to that described with reference to Figs. 1-4 with like components being identi-lied by like reference characters.

ReferringV to Figs. 7 and 8, binding p osts or conductors 4S and 49, having stationary contacts 5o and 5l formed on their respective inner ends, are brought out through openings 52 and 53 in the insulating housing portion ll. The front surface of the housing portion l is formed with a raised collar 54 which is formed with a central opening 54a to receive an insulating push-button 55 which is screwed on to a threaded extension S formed on the outer end of the push-shaft I5. Rating adjustment is effected by shifting the bushing 32 to displace the disc assembly all as described above.

It will be understood therefore that the various embodiments of the invention may be extensively modified without departing from the spirit and Scope of the invention which should not accordingly be limited save as deiined in the following claims.

We claim:

l. A circuit breaker assembly comprising a housing having a central cavity formed therein, a thermoresponsive snap spring disc mounted in the cavity for snap movement between two congurations, at least one contact element carried by the periphery of the disc, said contact having a portion extending beyond the margin of the disc, means defining al channel in the housing for receiving a portion of the contact extending beyond the margin of the disc, cooperative stationary contact meansmountedv in the housing and normally engaged by said contact element when the snap spring disc is in its rst configuration, and a carrier for displacing said disc in translation along the central axis of the disc and parallel to the directions of snap movement thereof, said channel4 being aligned with the directions ofsnap movement and translatory movement of the disc, whereby said contact element and channel constrain the disc against turning movement about the axis-cf the disc relatively to the housing.

2i In asnap switch assembly, in combination, a housing having a centralcavity formed therein, a thermoresponsive snap spring disc mounted in said cavity for peripheral snapy motion between two coniigurations, a pair of contact elements aiixed to the peripheryv of said disc at spaced paints andv electrically connected thereto, said contacts each having a portion extendingybeyond the margin of said disc,` means-defining channels in said housing for receiving the radially extending portions of said contact elements, said channels permitting snap movement oisaiddisc betweenits configurations and preventing turning movement about the mounting thereof, and a pair ci stationary contacts mountedA in the housing in cooperative relationship with thecontacts carried by the disc.`

3. A cord plugv assembly including a housing, a plurality of terminal connectors to afford an electrical connection with a mating electrical tting, a plurality of terminals in said housing for receiving individual conductors of an electrical cord, means providing an electricall connection between` corresponding cord terminals and terminal connectors, the electrical path between at least one cord terminal and terminal connector including a thermoresponsive snap spring member mounted in said housing for-control movement between rst and second configurations, first electrical contact meansl carried by said snap spring member and corresponding second electrical contact means carried by. said housing for engagement therewith toform a` closed electrical path through the device when thev snap spring member is in the irstl configuration, reset carrier means carrying said thermoresponsive snap spring member for eiectingrelative movement between the first and second electrical contact means and movement of the snap spring member from the second to the first configuration.

4. An electrical cord plug assembly including a housing, two or more conductor prongs extending outwardly from the housing for insertion in a plug receptacle, two or more terminals for receiving wires of an electrical cord, means affording an electrical path between corresponding prongs and terminals, at least one of said electrical paths including a bimetallic snap spring disc centrally mounted in said housing to enable its peripheral portions to partake of snap movement between two congurations, separable electrical Contact means adapted to be opened during snapping of said member from its first to its second configuration to open said electrical path, and a carrier for said disc movable between first and second positions to displace said snap disc in translational movement to induce snapping of said disc from its second to its first configuration to effect resetting.

5. A cord cap circuit breaker assembly including in combination a housing, a pair of conductor prongs extending outwardly from said housing, a pair of terminals for receiving the wires of an electrical cord, and switch means connected in series between at least one of said prongs and one of said terminals including a push-rod mounted for axial movement between rst and second positions, a bimetallic snap spring disc adapted to snap between rst and second coniigurations upon heating, said disc being centrally apertured to receive one end of said push-rod, spring means for urging said snap spring disc against the pushrod and also for urging said push-rod in the direction of its iirst position, a pair of spaced electrical contact elements carried by the Snap disc adjacent the periphery, a pair of stationary electrical contacts adapted to be engaged by the contact elements on the snap disc to form a closed circuit therebetween including the snap disc when the disc is in its rst configuration and the pushrod is in its iirst position, stationary abutment means in said housing adapted to be engaged by the peripheral portion of the snap disc when the snap disc is disposed in its second configuration of equilibrium and the push-rod is manually displaced in the direction of its second position, thereby to urge said disc to snap from its second to its iirst coniiguration and to maintain the engageable contacts spaced apart until said pushrod is returned to its iirst position.

6. A circuit breaker assembly yas set forth in claim 1, said carrier for the snap spring disc comprising a post, a bushing threaded into said housing substantially coaxially of said cavity for axial adjusting movement toward and away from said disc and centrally apertured to receive slidably said post, a stop shoulder on said post disposed between the ends thereof and adapted to engage the inner end of said bushing to determine one axial position of the post, said snap spring disc being centrally apertured to receive the inner end of said post, resilient means urging the center portion of said snap spring disc toward said stop shoulder and urging said stop shoulder toward the inner end of said bushing, and abutment means on said housing and disposed at the opposite end of said contact-receiving channel from the said stationary contact element to be engaged by the snap spring disc when the latter is in its second configuration, whereby said post may be urged inwardly to cause said stop shoulder and said abutment means to react against the disc to reverse the disc from its second to its rst configuration, and whereby axial adjusting movement of the bushing changes the thermoresponsive trip point of said disc from the rst to the second configuration.

7. A circuit breaker assembly comprising a housing having a cavity formed therein, a thermoresponsive snap spring member received in said cavity and adapted to snap from a rst to a second coniiguration under the influence of heat, a normally stationary bushing threaded into said housing to enter said cavity, said bushing being adjustable axially toward and away from said cavity, a post slidably received in said bushing 4and entering said cavity, a stop shouldei` on said post within said cavity and spaced axially away from the inner end of said post, said stop shoulder being adapted to engage the inner end of the bushing to limit the outward axial sliding movement of the post, said snap spring member being formed with an opening between its extremities to receive the inner end of said post, resilient means for urging said snap spring member toward said stop shoulder and for urging said post axially outwardly, electrical contact means controlled by snap action of said snap spring member between its two configurations, and abutment means on said housing adapted to be engaged by the extremities of said snap spring member when the post is moved inwardly and when the snap spring member is in its second coniiguration, said snap `spring member being adapted to be reacted between said stop shoulder and said abutment means to be reversed to its first conguration, the trip point of said snap spring member from its iirst to its second coniiguration being controlled by the axial adjustment of said bushing.

JOHN B. CATALDO. ELBERT DE F. TIDD. ALBERT N. COOK.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,293,179 Swingle Aug. 18, 1942 2,399,406 Toth Apr. 30, 1946 2,425,717 Bean Aug. 19, 1947 2,498,039 Gunn Feb. 21, 1950 2,508,637 Bolesky May 23, 1950 2,543,040 Mertler Feb. 27, 1951 

